单选题A plastic wheel can be as {{U}}tough{{/U}} as a metal one.

单选题Because of Delaware’s lenient laws regarding business incorporation, many companies have their {{U}}headquarters{{/U}} in the state’s largest city, Wilmington.

单选题I don't quite follow what she is saying A. believe B. understand C. explain D. accept

单选题The Best Way to Reduce Your Weight You hear this: "No Wonder you are fat. All you ever do is eat. " You feel sad: "I skip my breakfast and supper. I run every morning and evening. What else can I do?" Basically you can do nothing. Your genes, not your life habits, determine your weight and your body constantly tries to maintain it. Albert Stunkard of the University of Pennsylvania found from experiments that, "80 percent of the Children of two obese parents become obese, as compared with no more than 14 percent of the offspring of two parents of normal weight. " How can obese people become normal or even thin through dieting? Well, dieting can be effective, but the health costs are tremendous. Jules Hirsch, a research physician at Rockefeller University, did a study of eight fat people. They were given a liquid formula providing 600 calories (卡路里) a day. After more than 10 weeks, the subjects lost 45 kg on average. But after leaving the hospital, they all regained. The results were surprising: by metabolic measurement, fat people who lost large amounts of weight seemed like they were starving. They had psychiatric problems. They dreamed of food or breaking their diet. They were anxious and depressed (沮丧的) ; some were suicidal. They hid food in their rooms. Researchers warn that it is possible that weight reduction doesn't result in normal weight, but in an abnormal state resembling (类似) that of starved non-obese people. Thin people, however, suffer from the opposite: They have to make a great effort to gain weight. Ethan Sims, of the University of Vermont, got prisoners to volunteer to gain weight. In four to six months, they ate as much as they could. They succeeded in increasing their weight by 20 to 25 percent. But months after the study ended, they were back to normal weight and stayed there. This did not mean that people are completely without hope in controlling their weight. It means that those who tend to be fat will have to constantly battle their genetic inheritance if they want to significantly lower their weight. The findings also provide evidence for something scientists thought was true -- each person has a comfortable weight range. The range might be as much as 9 kg. Someone might weigh 60-69 kg without too much effort But going above of below the natural weight range is difficult. The body resists by feeling hungry or full and changing the metabolism to push the weight back to the range it seeks.

单选题All living organisms, {{U}}regardless of{{/U}} their unique identity, have certain biological, chemical, and physical characteristics in common.

单选题His imagination transformed shadows into a monster. A. a beast B. a ghost C. a giant D. an angel

单选题I am sure to tell you that there"s no danger.

单选题Longer Lives for Wild Elephants Most people think of zoos as safe places for animals, where struggles such as difficulty finding food and avoiding predators don"t exist. Without such problems, animals in zoos should live to a ripe old age. But that may not be true for the largest land animals on Earth. Scientists have known that elephants in zoos often suffer from poor health. They develop diseases, joint problems and behavior changes. Sometimes, they even become infertile, or unable to have babies. To learn more about how captivity affects elephants, a team of international scientists compared the life spans of female elephants born in zoos with female elephants living outdoors in their native lands. Zoos keep detailed records of all the animals in their care, documenting factors such as birth dates, illnesses, weight and death. These records made it possible for the researchers to analyze 40 years of data on 800 African and Asian elephants in zoos across Europe. The scientists compared the life spans of the zoo-born elephants with the life spans of thousands of female wild elephants in Africa and Asian elephants that work in logging camps, over approximately the same time period. The team found that female African elephants born in zoos lived an average of 16.9 years. Their wild counterparts who died of natural causes lived an average of 56 years—more than three times as long. Female Asian elephants followed a similar pattern. In zoos, they lived 18.9 years, while those in the logging camps lived 41.7 years. Scientists don"t yet know why wild elephants seem to fare so much better than their zoo-raised counterparts. Georgia Mason, a biologist at the University of Guelph in Canada who led the study, thinks stress and obesity may be to blame. Zoo elephants don"t get the same kind of exercise they would in the wild, and most are very fat. Elephant social lives are also much different in zoos than in the wild, where they live in large herds and family groups. Another finding from the study showed that Asian elephants born in zoos were more likely to die early than Asian elephants captured in the wild and brought to zoos. Mason suggests stress in the mothers in zoos might cause them to have babies that are less likely to survive. The study raises some questions about acquiring more elephants to keep in zoos. While some threatened and endangered species living in zoos reproduce successfully and maintain healthy populations, that doesn"t appear to be the case with elephants. "Currently, zoos are net consumers of elephants, not net producers," Mason says.

单选题Michael is now merely a good friend.

单选题The boys broke into excited cheering.

单选题U.S. to Start $ 3.2 Billion Child Health Study in January A study that will cost $ 3.2 billion and last more than two decades to track the health of 100,000 U. S. children from before birth to age 21 will be launched in January, U. S. health officials said on Friday. Officials from the U. S. government's National Institutes of Health said they hope the study, to be conducted at 105 locations throughout the United States, can help identify early-life influences that affect later development, with the goal of learning new ways to treat or prevent illness. The study will examine hereditary(遗传的) and environmental factors such as exposure to certain chemicals that affect health. Researchers will collect genetic and biological samples from people in the study as well as samples from the homes of the women and their babies including air, water, dust and materials used to construct their residences, the NIH said. Officials said more than $ 200 million has been spent already and the study is projected to cost $3.2 billion. "We anticipat that in the long term(从长远来说), what we learn from the study will result in a significant savings in the nation's health care costs," Dr. Duane Alexander, who heads the NIH's Eunice Kennedy Shriver National Institute of Child Health and Human Development, told reporters. The study will begin in January. when the University of North Carolina and the Mount Sinai School of Medicine in New York start signing up(使报名从事) pregnant women whose babies will then be followed to age 21. Some of the early findings will be 'about factors behind pre-term birth(早产), which has become more common in recent years, according to Dr. Peter Scheidt of the NIH, who heads the study. The people taking part will be from rural, urban and suburban areas, from all income and educational levels and from all racial groups, the NIH said.

单选题What were the {{U}}consequences{{/U}} of the decision she had made?

单选题Older Volcanic Eruptions Volcanoes were more destructive in ancient history, not because they were bigger, but because the carbon dioxide they released wiped out life with greater ease. Paul Wignall from the University of Leeds was investigating the link between volcanic eruptions and mass extinctions. Not all volcanic eruptions killed off large numbers of animals, but all the mass extinctions over the past 300 million years coincided with huge formations of volcanic rock. To his surprise, the older the massive volcanic eruptions were, the more damage they seemed to do. He calculated the "killing efficiency" for these volcanoes by comparing the proportion of life they killed off with the volume of lava (熔岩) that they produced. He found that size for size, older eruptions were at least 10 times as effective at wiping out life as their more recent rivals. The Permian (二叠纪) extinction, for example, which happened 250 million years ago, is marked by floods of volcanic rock in Siberia that cover an area roughly the size of western Europe. Those volcanoes are thought to have pumped out about 10 gigatonnes (十亿吨) of carbon as carbon dioxide. The global warming that followed wiped out 80 percent of all marine genera (种类) at the time, and it took 5 million years for the planet to recover. Yet 60 million years ago, there was another huge amount of volcanic activity and global warming but no mass extinction. Some animals did disappear but things returned to normal within ten thousands of years. "The most recent ones hardly have an effect at all," Wignall says. He ignored the extinction which wiped out the dinosaurs 65 million years ago, because many scientists believe it was primarily caused by the impact of an asteroid (小行星). He thinks that older volcanoes had more killing power because more recent life forms were better adapted to dealing with increased levels of CO 2 . Vincent Courtillot, director of the Paris Geophysical Institute in France, says that Wignall"s idea is provocative. But he says it is incredibly hard to do these sorts of calculations. He points out that the killing power of volcanic eruptions depends on how long they lasted. And it is impossible to tell whether the huge blasts lasted for thousands or millions of years. He also adds that it is difficult to estimate how much lava prehistoric volcanoes produced, and that lava volume may not necessarily correspond to carbon dioxide emissions.

单选题After the accident, my back was very painful for a long time. A. was a pain B. hurt a lot C. was injured D. wounded me

单选题Paper or Plastic? Take a walk along the Chesapeake Bay, and you are likely to see plastic bags floating in the water. Ever since these now ubiquitous (到处存在的) symbols of American super-consumption showed up in the supermarkets, plastic shopping bags have made their (51) into local waterways, and from there, into the bay, where they can (52) wildlife. Piles of them - the (53) takes centuries to decompose (分解) -- show up in landfills and on city streets. Plastic bags also take an environmental toll in the form of millions of barrels of oil expended every year to produce them. Enter Annapolis (54) you will see plastic bags distributed free in department stores and supermarkets. Alderman Sam Shropshire has introduced a well-meaning proposal to ban retailers (零售商) (55) distributing plastic shopping bags in Maryland's capital. Instead, retailers would be required to offer bags (56) recycled paper and to sell reusable bags. The city of Baltimore is considering a similar measure. Opponents of the idea, however, argue that (57) bags are harmful, too: they cost more to make, they consume more (58) to transport, and recycling them causes more pollution than recycling plastic. The argument for depriving Annapolis residents (居民) of their plastic bags is (59) accepted. Everyone in this (60) is right about one thing: disposable shopping bags of any type are (61) , and the best outcome would be for customers to reuse bags instead. Annapolis's mayor is investigating how to hand out free, reusable (可以再度使用的) shopping bags to city residents, a proposal that can proceed regardless of whether other bags are banned. A less-expensive (62) would be to encourage retailers to give discounts to customers (63) bring their own, reusable bags, a policy that a spokesman for the supermarket Giant Food says its chain already has in place. And this policy would be more (64) if stores imitated furniture mega-retailer Ikea and charged for disposable bags at the checkout counter. A broad ban on the use of plastic shopping bags, which would merely replace some forms of pollution with others, is not the (65) .

单选题The news will {{U}}horrify{{/U}} everyone. A.attract B.terrify C.tempt D.excite

单选题The company has the right to end his employment at any time.

单选题Compared with the clear words of her boyfriend on screen, his accent is

单选题下面有3篇短文，每篇短文后有5道题，每题后面有4个选项。请仔细阅读短文并根据短文回答其后面的问题，从4个选项中选择1个最佳答案。{{B}}第一篇{{/B}} Unless we spend money to spot and prevent asteroids(小行星) now, one might crash into Earth and destroy life as we know it, say some scientists. Asteroids are bigger versions of the meteoroids(流星) that reace across the night sky. Most orbit the sun far from Earth and don't threaten us. But there are also thousands of asteroids whose orbits put them on a collision course with Earth. Buy $ 50 million worth of now telescopes right now. Then spend $ 10 million a year for the next 25 years to locate most of the space rocks. By the time we spot a fatal one, the scientists say, we'll have a way to change its course. Some scientists favor pushing asteroids off course with nuclear weapons. But the cost wouldn't be cheap. Is it worth it? Two things experts consider when judging any risk are: 1) How likely the event is; and 2) How bad the consequences if the event occurs. Experts think an asteroid big enough to destroy lots of life might strike Earth once every 500,000 years. Sounds pretty rare— but if one did fall, it would be the end of the world. "If we don't take care of these big asteroids, they'll take care of us," says one scientist. "It' s that simple." The cure, though, might be worse than the disease. Do we really want fleets of nuclear weapons sitting around on Earth? "The world has less to fear from doomsday(毁灭性) rocks than from a great nuclear fleet set against them," said a New York Times article.

单选题In order to improve our standard of living, we have to Uaccelerate/U production.